Various kinds of image processing are employed for facilitating observation of an object to be observed included in an image. For example, such image processing performed on an image including a linear signal serving as an observed object is known that emphasizes the linear signal and controls elements (such as a background) other than the linear signal by separating the linear signal from the elements other than the linear signal. As an example, such an image processing method is known that removes a low-frequency component from an image, extracts a high-frequency image including a high-frequency component where a linear signal is classified, detects the linear signal using the extracted high-frequency image, and performs emphasizing processing and the like on the detected linear signal.
Use of the above-described image processing method can, for example, accurately detect a linear structural object such as a catheter on a fluoroscopic image imaged by an X-ray diagnostic apparatus and display the object. With the above-described conventional technique, however, visibility of an image including a linear signal is likely to decrease.